Noise shaping is a method enabling increasing the apparent signal to noise ratio (SNR) of the resultant signal. In detail, the spectral shape of a signal is changed such that the noise power is reduced to lower levels in frequency bands where noise is perceived to be more undesirable and correspondingly increased in frequency bands in which the noise is perceived to be less undesirable. The background of such noise shapers is the well-known Nyquist theorem stating that for real signals the sampling rate should be at least twice as high as the highest signal frequency. Therefore, the frequency half of the sampling frequency is often called the Nyquist frequency. In a lot of situations the actually used sampling frequency is much higher than the Nyquist frequency. This provides some freedom which may be used for noise shaping. Expressed in other words, this means that the quantization noise inside the wanted frequency range is reduced for the price that the noise outside this frequency range is increased to higher values.